When, after an injury or harm allegedly caused by an event, measures are taken that, if taken previously, would have made the injury or harm less likely to occur, evidence of the subsequent measures is not admissible to prove negligence, culpable conduct, a defect in a product, a defect in a product's design, or a need for a warning or instruction. This rule does not require the exclusion of evidence of subsequent measures when offered for another purpose, such as proving ownership, control, or feasibility of precautionary measures, if controverted, or impeachment.

Missouri doesn't have codified rules of evidence (and while the Missouri constitution authorizes the Supreme Court of Missouri to create rules, that authorization specifically excludes rules of evidence). That said, Missouri courts have in effect applied Federal Rule of Evidence 407 in their precedent, and in its recent opinion in Rader Family Ltd. Partnership, L.L.L.P. v. City of Columbia, 2009 WL 1439017 (Mo.App. W.D. 2010), the Missouri Court of Appeals, Western District, found that the exclusionary portion of this Rule applies in nuisance cases generally and inverse condemnation cases specifically.

In Rader, the sewer backed up into the finished basement of a downtown building owned by Rader. It was later determined that the cause of the backup was grease in the sewer line and that the grease originated from restaurants upstream of the blockage. After incurring cleanup and removal costs, Rader sued the City of Columbia under, inter alia, a theory of inverse condemnation, contending that its building had been reduced in value because of the damage to the basement. At trial, Rader sought to present evidence of measures the City implemented to prevent grease-related sewage backups after Rader's building was damaged, but the trial court deemed this evidence inadmissible.

After the jury entered a verdict in favor of the City, Rader appealed, claiming, inter alia, that the trial court erred in deeming this evidence inadmissible. In response, the Missouri Court of Appeals, Western District, quoted the language of Federal Rule of Evidence 407 and noted that

Two primary reasons for the rule are: (1) "if precautions taken could be used as evidence of previous improper conditions, no one, after an accident, would make improvements"; and (2) subsequent changes are irrelevant to proving the previous condition.

The court then noted that the case before it was not the classic case of subsequent remedial measures being excluded when a plaintiff claims negligence and that the rule does not apply to all tort claims. The court then noted that the issue of whether evidence of subsequent remedial measure is admissible in nuisance/inverse condemnation cases was an issue of first impression in Missouri. And the court decided that such evidence is inadmissible in such cases, holding

we believe the public policy rationale for the exclusion applies here, perhaps even more so than in a typical negligence case. If plaintiffs were allowed to introduce evidence of subsequent remedial measures to prove a prior nuisance by an entity with the power of eminent domain, this could deter these entities from implementing preventative measures protecting the public. We also believe the evidentiary rationale has some application to inverse condemnation cases: while that the entity subsequently takes preventative measures could be probative of whether its prior operation was reasonable, such measures are not pertinent to showing the entity had prior notice of a problem. Hence, the trial court's decision to apply the rule against admission of subsequent remedial measures to this inverse condemnation suit was not arbitrary, unreasonable, or against the logic of the circumstances.